BG-RAG: Concept-Mediated Bipartite Graphs for Scalable RAG

Hang Gao, Yangmin Ding, Shaobo Han, Zhuocheng Jiang


Abstract
Graph-structured retrieval-augmented generation (GraphRAG) has shown strong potential for improving multi-hop reasoning in large language models. However, existing approaches typically depend on dense entity–entity linking, which is computationally expensive, susceptible to hallucinated relations, and difficult to maintain under continual updates. We present Bipartite Graph Retrieval-Augmented Generation (BG-RAG), a lightweight bipartite framework that organizes knowledge into three layers, from chunks to entities to concepts, and replaces direct entity links with concept-mediated connections. This design enables more efficient graph construction, reduces reliance on hallucination-prone relation-edge prediction by avoiding explicit entity–entity relation extraction, and naturally supports incremental updates without global reconstruction. Experiments on HotpotQA, 2Wiki, and MuSiQue show that BG-RAG achieves competitive performance against RAG and GraphRAG baselines. Its concept-mediated structure also provides a lightweight alternative to dense entity–entity graph construction. These results suggest that BG-RAG is a lightweight alternative for retrieval-augmented generation, particularly when avoiding dense entity–entity linking is desirable.
Anthology ID:
2026.aacl-short.58
Volume:
Proceedings of the 15th International Joint Conference on Natural Language Processing and the 5th Conference of the Asia-Pacific Chapter of the Association for Computational Linguistics (Volume 2: Short Papers)
Month:
November
Year:
2026
Address:
Hengqin, China
Editors:
Yue Zhang, Ruifeng Xu, Ayu Purwarianti, Tong Rong, Jun Suzuki
Venues:
AACL | IJCNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
917–922
Language:
URL:
https://aclanthology.org/2026.aacl-short.58/
DOI:
Bibkey:
Cite (ACL):
Hang Gao, Yangmin Ding, Shaobo Han, and Zhuocheng Jiang. 2026. BG-RAG: Concept-Mediated Bipartite Graphs for Scalable RAG. In Proceedings of the 15th International Joint Conference on Natural Language Processing and the 5th Conference of the Asia-Pacific Chapter of the Association for Computational Linguistics (Volume 2: Short Papers), pages 917–922, Hengqin, China. Association for Computational Linguistics.
Cite (Informal):
BG-RAG: Concept-Mediated Bipartite Graphs for Scalable RAG (Gao et al., AACL-IJCNLP 2026)
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PDF:
https://aclanthology.org/2026.aacl-short.58.pdf